Surgery supporting apparatus for controlling motion of robot arm

ABSTRACT

A surgery supporting apparatus is capable of controlling a posture of a surgical instrument that is inserted into a body cavity and mechanically drivable. The apparatus includes a robot arm that can control the posture of the surgical instrument, which is attached to the robot arm via a gimbal mechanism.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a Continuation of application Ser. No. 16/658,344 filed Oct. 21,2019, which claims priority to and the benefit of Japanese PatentApplication No. 2018-199386 filed on Oct. 23, 2018. The disclosure ofthe prior applications is hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

This application relates to a surgery supporting apparatus forcontrolling motion of a robot arm, a control method of the same, and anon-transitory computer-readable storage medium.

BACKGROUND

A laparoscopic surgery is generally performed by a doctor (to bereferred to as “an operator” hereinafter) who performs incision,excision, and suture of an organ, a doctor (to be referred to as “ascopist” hereinafter) who holds an endoscope, and a doctor (to bereferred to as “an assistant” hereinafter) who performs, for example,organ retraction to increase visibility for the operator, and tensionretainment during incision. Some surgery supporting apparatuses (alsocalled surgery supporting robots) for use in a laparoscopic surgeryreduce the number of doctors necessary for the surgery by controllingthe postures of surgical instruments such as forceps, an endoscope, andan electric scalpel by using one or more robot arms.

The manipulation of a surgery supporting apparatus includes a consoletype manipulation by which a doctor manipulates a surgery supportingapparatus from a control unit of the apparatus, and a method by which anoperator controls, for example, a robot arm for holding only anendoscope while performing a surgical procedure by some method.

Conventional surgery supporting apparatuses to be used in a laparoscopicsurgery are roughly classified into an apparatus that performs motionsof three doctors, that is, an operator, a scopist, and an assistant, andan apparatus that holds an endoscope with one arm. The apparatus thatfunctions as an operator, a scopist, and an assistant is a console typesurgery supporting robot, and robots including a plurality of robot armsarranged around and over a patient are known (Japanese Patent Laid-OpenNos. 2011-4880 and 2017-104455).

On the other hand, a surgery supporting robot that holds only anendoscope by using one robot arm is also known (Japanese PatentLaid-Open No. H6-30896). This surgery supporting robot disclosed inJapanese Patent Laid-Open No. H6-30896 requires no console formanipulations, and uses a method by which an operator or an assistantmanipulates the robot by voices.

The console type surgery supporting robot disclosed in Japanese PatentLaid-Open No. 2011-4880 has a large apparatus size, and this sometimesmakes it difficult to optimize the positional relationship between apatient and the robot, depending on a balance with another apparatus inan operating room. Also, it is sometimes possible to remotely manipulatethe console type robot, but a manipulation console is usually installedin an operating room in which a patient and the robot exist, in order toobserve the outer appearance of the patient and communicate with nurses.This is one cause of oppressing the operating room. Even when theapparatus size of the console type surgery supporting robot disclosed inJapanese Patent Laid-Open No. 2017-104455 is decreased, a largecomplicated console is necessary to manipulate many multijoint robotarms.

The apparatus size of the surgery supporting robot disclosed in JapanesePatent Laid-Open No. H6-30896 can be decreased because a manipulationtarget is one arm robot. However, the robot still requires works by anassistant and the like, and the robot arm approaches a plurality ofhumans. This makes it impossible to secure a sufficient robot armoperational area, or the robot arm interferes with an operator or anassistant and influences an operation procedure. Also, when using thevoice manipulating means, it is easy to imagine that when manipulating acomplicated surgical instrument different from an endoscope, it isdifficult to manipulate the surgical instrument as intended.

SUMMARY

The present disclosure has been made in consideration of theaforementioned issues, and realizes a surgery supporting apparatus notrequiring a console that is difficult to install in an operating room,and capable of simply manipulating a robot arm.

In order to solve the aforementioned problems, one aspect of the presentdisclosure provides a surgery supporting apparatus capable ofcontrolling a posture of a first surgical instrument that is insertedinto a body cavity and mechanically drivable, by using a second surgicalinstrument to be inserted into the body cavity, comprising: a robot armconfigured to control the posture of the first surgical instrumentattached to the robot arm; one or more processors; and a memory storinginstructions which, when the instructions are executed by the one ormore processors, cause the surgery supporting apparatus to function as:a switching unit configured to switch motion modes for controlling amotion of the robot arm; and a control unit configured to control themotion of the robot arm in accordance with the motion mode, wherein themotion mode includes a first mode in which the second surgicalinstrument is used to control the first surgical instrument, and asecond mode in which the robot arm is moved by a manipulation includingcontact to the robot arm, and the control unit controls the motion ofthe robot arm such that the posture of the first surgical instrument iscontrolled in accordance with the posture of the second surgicalinstrument, in a case where the motion mode is the first mode, andcontrols the motion of the robot arm in accordance with the manipulationincluding contact to the robot arm, in a case where the motion mode isthe second mode.

Another aspect of the present disclosure provides, a control method of asurgery supporting apparatus capable of controlling a posture of a firstsurgical instrument that is inserted into a body cavity and mechanicallydrivable, by using a second surgical instrument to be inserted into thebody cavity, the surgery supporting apparatus including a robot armconfigured to control the posture of the first surgical instrumentattached to the robot arm, and the control method comprising: switchingmotion modes for controlling a motion of the robot arm; and controllingthe motion of the robot arm in accordance with the motion mode, whereinthe motion mode includes a first mode in which the second surgicalinstrument is used to control the first surgical instrument, and asecond mode in which the robot arm is moved by a manipulation includingcontact to the robot arm, and in the controlling, the motion of therobot arm is controlled such that the posture of the first surgicalinstrument is controlled in accordance with the posture of the secondsurgical instrument, in a case where the motion mode is the first mode,and the motion of the robot arm is controlled in accordance with themanipulation including contact to the robot arm, in a case where themotion mode is the second mode.

Still another aspect of the present disclosure provides, anon-transitory computer-readable storage medium storing a program forcausing a computer to execute a control method of a surgery supportingapparatus capable of controlling a posture of a first surgicalinstrument that is inserted into a body cavity and mechanicallydrivable, by using a second surgical instrument to be inserted into thebody cavity, the surgery supporting apparatus including a robot armconfigured to control the posture of the first surgical instrumentattached to the robot arm, and the control method comprising: switchingmotion modes for controlling a motion of the robot arm; and controllingthe motion of the robot arm in accordance with the motion mode, whereinthe motion mode includes a first mode in which the second surgicalinstrument is used to control the first surgical instrument, and asecond mode in which the robot arm is moved by a manipulation includingcontact to the robot arm, and in the controlling, the motion of therobot arm is controlled such that the posture of the first surgicalinstrument is controlled in accordance with the posture of the secondsurgical instrument, in a case where the motion mode is the first mode,and the motion of the robot arm is controlled in accordance with themanipulation including contact to the robot arm, in a case where themotion mode is the second mode.

According to the disclosed embodiments, it is possible to provide asurgery supporting apparatus not requiring a console that is difficultto install in an operating room, and capable of simply manipulating arobot arm.

Further features of the disclosed embodiments will become apparent fromthe following description of exemplary embodiments (with reference tothe attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate disclosed embodiments.

FIGS. 1A and 1B are views showing an overall configuration example of asurgery supporting apparatus according to the disclosed embodiments;

FIG. 2A is a functional configuration example of a surgery supportingapparatus according to an embodiment;

FIG. 2B is a view schematically showing the way a handheld medicalinstrument and a robot medical instrument are inserted into a bodycavity when using the surgery supporting apparatus according to theembodiment;

FIG. 3 is a view showing a detailed configuration example of ahorizontal robot arm according to the embodiment;

FIG. 4 is an enlarged view of the distal end portion of the horizontalrobot arm according to the embodiment;

FIG. 5 is a view showing a configuration example of a linear-motionjoint of the horizontal robot arm according to the embodiment;

FIGS. 6A and 6B are views for explaining a grip with a brake releaseswitch according to the embodiment;

FIGS. 7A to 7C are views showing internal structure examples when thebrake release switch according to the embodiment is viewed in thevertical direction;

FIG. 8 is a view showing an example of an input switch on the side of asurgical instrument manipulator for a vector manipulation mode accordingto the embodiment;

FIG. 9 is a view showing a mechanism equivalent model of the horizontalrobot arm according to the embodiment;

FIG. 10 is a view showing a detailed configuration example of alinear-motion robot arm according to the embodiment;

FIG. 11 is a view showing a configuration example of a vertical drivingjoint of the linear-motion robot arm according to the embodiment;

FIG. 12 is a view showing a mechanism equivalent model of thelinear-motion robot arm according to the embodiment;

FIG. 13 is a view schematically showing the relationship between thefirst arm of the linear-motion robot arm and two frames according to theembodiment;

FIGS. 14A and 14B are views showing details of the relationship betweenthe first arm of the linear-motion robot arm and the two framesaccording to the embodiment;

FIGS. 15A and 15B are views each for explaining the movable range of thearm distal end portion of a robot arm according to the embodiment;

FIG. 16 is a view for explaining initialization according to theembodiment;

FIG. 17 is a flowchart showing a series of operations of aninitialization process according to the embodiment; and

FIG. 18 is a view for explaining a method of calculating the position ofan insertion point according to the embodiment.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the disclosed embodiments will be explained indetail below with reference to the accompanying drawings. A surgerysupporting apparatus according to the disclosed embodiments includes arobot arm for controlling the posture of a surgical instrument or an endeffector inserted into the body cavity of a patient through a sheathtube. The surgery supporting apparatus measures the insertion angle andthe insertion depth of a surgical instrument (to be also referred to asa handheld medical instrument hereinafter) to be inserted into the bodycavity and actually used in a surgery by an operator. In accordance withthe measurement results, the surgery supporting apparatus controls arobot arm 100 for controlling the posture of a surgical instrument or anend effector (both of which will also be referred to as robot medicalinstruments hereinafter).

(Outline of Robot Arm 100 According to Surgery Supporting Apparatus)

FIG. 1A shows an outline of the robot arm 100 of the surgery supportingapparatus according to the disclosed embodiments, and FIG. 1B shows apatient, an operator, and an operating table 151 when using a surgerysupporting apparatus 200 assumed in this embodiment. The robot arm 100according to this embodiment includes two horizontal robot arms 110, alinear-motion robot arm 120, and a plurality of frames (bases).

A first frame 101 includes one or both of an active wheel and a passivewheel so as to arrange a patient and the robot arm 100 at an appropriatedistance. A second frame 102 is fixed on the first frame 101, and athird frame 103 is connected to the second frame 102 by a part having adegree of freedom in only the vertical direction. Two 3-axis horizontalmultijoint robot arms (to be simply referred to as horizontal robot arms110) including joints having a degree of freedom in the horizontaldirection are attached to the third frame 103. In addition, a 3-axislinear-motion multijoint robot arm (to be also simply referred to as alinear-motion robot arm 120) is connected to the distal end of the thirdframe 103 by a part having a degree of freedom in only the verticaldirection.

A surgical instrument manipulator 124 is attached to the distal end ofthe horizontal robot arm 110 via a gimbal mechanism capable of rotatingaround two axes. The surgical instrument manipulator 124 is a drivingdevice for controlling the position and posture of the distal endportion of a robot medical instrument whose insertion angle andinsertion depth with respect to a body cavity are controlled by thehorizontal robot arm 110. The surgical instrument manipulator 124includes a plurality of motors for generating a plurality of independentrotating powers, and each power is transmitted to the distal end portionof a robot medical instrument through, for example, a shaft of the robotmedical instrument.

In the horizontal robot arm 110, a first arm 111 and a second arm 112are connected by an active joint having a degree of freedom in onlyhorizontal rotation, and the second arm 112 and a third arm 113 areconnected by an active joint having a degree of freedom in onlyhorizontal rotation. The first arm 111 includes an active joint having adegree of freedom in the vertical direction (the major-axis direction ofthe third frame 103), and hence can move the second arm 112 and thethird arm 113 in the vertical direction. Since this makes it possible tothree-dimensionally move a robot medical instrument connected to thesurgical instrument manipulator at the hand of the horizontal robot arm110, the angle and depth of insertion of the robot medical instrumentinto a body cavity are controlled. The arrangement of the horizontalrobot arm will be described in more detail later.

Like the horizontal robot arm 110, the distal end of the linear-motionrobot arm 120 has a gimbal mechanism capable of rotating around twoaxes. The linear-motion robot arm 120 includes an endoscope holdercapable of attaching a general endoscope to the gimbal mechanism. In thelinear-motion robot arm 120, a third arm 123 and a second arm 122 areconnected by an active joint having a degree of freedom in thehorizontal direction, and the second arm 122 and a first arm 121 areconnected by an active joint having a degree of freedom in horizontalrotation. Since the first arm 121 is connected to an active joint havinga degree of freedom in the vertical direction (the major-axis directionof the third frame 113), the second arm 122 and the third arm 123 canmove in the vertical direction. Since this makes it possible tothree-dimensionally move an endoscope (robot medical instrument)connected to an endoscope holder 114 at the hand of the linear-motionrobot arm 120, the angle and depth of insertion of the endoscope (robotmedical instrument) into a body cavity are controlled.

(Arrangement of Surgical Supporting Apparatus 200)

FIG. 2A schematically shows a functional configuration example of thesurgery supporting apparatus 200 according to this embodiment, and FIG.2B schematically shows the way a handheld medical instrument and a robotmedical instrument are inserted into a body cavity when using thesurgery supporting apparatus 200. The surgery supporting apparatus 200is not a general console type master-slave apparatus, but controls themotion of a robot arm based on the motion of a surgical instrument (thatis, a handheld medical instrument) which an operator uses during asurgery.

A handheld medical instrument 131 is a surgical instrument which anoperator actually moves by the hand to perform an ordinary treatment,and is inserted into a body cavity through an operator-side sheath tube135 inserted into a small-diameter hole formed in an abdominal wall 150.The handheld medical instrument 131 includes, for example, a forceps, apair of tweezers, an electric scalpel, an aspiration tube, anultrasonically activated scalpel, a hemostatic device, a radiofrequencyablation device, a medical stapler, and a needle holder to be insertedinto a body cavity. A surgical instrument motion measurement unit 132attached to the handheld medical instrument 131 and an operator-sideinsertion depth measurement unit 136 attached to the operator-sidesheath tube 135 measure the angle and depth of insertion of the handheldmedical instrument 131 into the body cavity.

A part of a robot medical instrument 127 is inserted into the bodycavity through a robot-side sheath tube 125 inserted into asmall-diameter hole formed in the abdominal wall 150. For example, therobot medical instrument 127 includes a forceps, a pair of tweezers, anelectric scalpel, an aspiration tube, an ultrasonically activatedscalpel, a hemostatic device, a radiofrequency ablation device, amedical stapler, a needle holder, an endoscope, a thoracoscope, and alaparoscope to be inserted into a body cavity. The robot medicalinstrument 127 can have a straight shape, and can also have a bendingjoint. In an example of this embodiment, an endoscope as the robotmedical instrument 127 is attached to the linear-motion robot arm 120via the endoscope holder 114. Also, a forceps, an electric scalpel, orthe like is attached as the robot medical instrument 127 to thehorizontal robot arm 110 via the surgical instrument manipulator 124.The posture of the distal end of the medical instrument such as aforceps attached via the surgical instrument manipulator 124 iscontrolled by driving the surgical instrument manipulator 124. Note thatin this embodiment, a simple term “robot arm” means that the robot armincludes the surgical instrument manipulator 124. Note also that anexplanation will be made by taking, as an example, a case in which therobot medical instrument 127 and the surgical instrument manipulator 124are different members, but the robot medical instrument 127 and thesurgical instrument manipulator 124 may also be integrated as a surgicalinstrument.

A robot-side insertion depth measurement unit 126 can detect that therobot arm is inserted into the robot-side sheath tube 125. Also, one ormore distance sensors attached to the robot-side sheath tube 125 measurethe depth of insertion, into the body cavity, of the robot medicalinstrument 127 that is controlled by the horizontal robot arm 110 or thelinear-motion robot arm 120. Note that the robot-side insertion depthmeasurement unit 126 can also detect only the insertion of the robot arminto the robot-side sheath tube 125. In this case, position/postureinformation can be obtained in accordance with the output from anencoder of the robot arm. Furthermore, the robot-side insertion depthmeasurement unit 126 can separately be attached to the robot-side sheathtube 125 and the robot medical instrument 127, like a transmitter and areceiver, and can also be attached to only the robot medical instrument127.

The surgical instrument motion measurement unit 132 includes one or acombination of, for example, an acceleration sensor, an ultrasonicsensor, a geomagnetic sensor, a laser sensor, and an optical motioncapture, and detects 3-axis to 6-axis surgical instrument motions. Inthis embodiment, the surgical instrument motion measurement unit 132measures, for example, the angle of insertion, into a body cavity, of ahandheld medical instrument to be manipulated by an operator.

The operator-side insertion depth measurement unit 136 includes one ormore distance sensors attached to the operator-side sheath tube 135, andmeasures the depth of insertion of the handheld medical instrument 131into a body cavity. In this embodiment, an example in which theoperator-side insertion depth measurement unit 136 is attached to theoperator-side sheath tube 135 will be explained. However, theoperator-side insertion depth measurement unit 136 can separately beattached to the operator-side sheath tube 135 and the handheld medicalinstrument 131, like a transmitter and a receiver, and can also beattached to only the handheld medical instrument 131.

A control unit 201 includes one or more processors such as a CPU or aGPU, and controls the overall manipulation of the surgery supportingapparatus 200 by reading out a program stored in a storage medium 204 toa memory 205 and executing the readout program. The control unit 201also functions as a switching unit (switch) for switching manipulationmodes of the surgery supporting apparatus based on a manipulationperformed on a manipulation unit 202. Furthermore, the control unit 201functions as a control unit for controlling the manipulation of a robotarm so as to control the posture of a robot medical instrument inaccordance with the insertion angle and the insertion depth of the shaftof the handheld medical instrument 131 with respect to a body cavity.The manipulation modes of the surgery supporting apparatus include amode (to be also simply referred to as a treatment mode) in which atreatment is actually performed by manipulating the handheld medicalinstrument 131, and a mode (to be also simply referred to as a robotmanipulation mode) in which the robot medical instrument 127 ismanipulated by using the handheld medical instrument 131. As will bedescribed in detail later, the manipulation modes also include a mode inwhich an operator manipulates a robot arm by a manipulation includingcontact to the robot arm.

The manipulation unit 202 includes manipulation members such as a switchto be attached to the handheld medical instrument 131, and a foot switchwhich an operator can manipulate with his or her foot. Instead of theswitch, the manipulation unit 202 can further include a voice inputsystem by which a manipulation can be input by a voice. In accordancewith an input from the manipulation unit 202, the control unit 201changes the manipulation mode of the surgery supporting apparatus 200,changes an arm to be controlled, and changes information to be displayedon a display unit 203. For example, an operator can select one arm as acontrol target by using the manipulation unit 202.

As described above, the robot medical instrument 127 can be manipulatedin accordance with the motion of the handheld medical instrument 131manipulated by an operator. Therefore, while three doctors usuallyperform a conventional laparoscopic surgery, an operator can perform asimilar surgery by manipulating the robot arm although the manipulationis equal to that of a surgery performed by manipulating a surgicalinstrument.

(Details of Horizontal Robot Arm 110)

<Horizontal Driving Joint>

Details of the horizontal robot arm 110 will be explained with referenceto FIGS. 3 to 8 . As shown in FIG. 3 , the distal end portion (of thethird arm 113) of the horizontal robot arm 110 has a 2-axis gimbalmechanism 301 to which the surgical instrument manipulator 124 can beattached. FIG. 4 shows the distal end portion (of the third arm 113) ofthe horizontal robot arm 110 in an enlarged scale. The gimbal mechanism301 can rotate around two rotating axes 401 and 402 shown in FIG. 4 ,and the two rotating axes 401 and 402 intersect an axis 403 of thesurgical instrument shaft of a robot medical instrument attached to thesurgical instrument manipulator 124. The gimbal mechanism 301 is apassive joint having no power unit, but includes an encoder formeasuring rotation around each rotating axis. For example, it ispossible, by using absolute encoders for both of the two axes, to obtainthe position and posture of the robot medical instrument 127 by usingthe forward kinematics. Also, the horizontal robot arm 110 can use anelastic mechanism (for example, a damper, a resin spring, or a metalspring in the rotational direction) or an auxiliary power in order tosuppress the influence of slight vibrations during manipulation orslight motions caused by the respiration of a patient, thereby achievinga function of stabilizing the posture or avoiding a unique posture.

A third arm driving unit 302 contained in the second arm 112 includes adriving motor for driving the third arm 113, a spring-actuated brake,and a speed reducer. The third arm 113 and the second arm 112 have adegree of freedom in only horizontal rotation, and the third arm 113 canactively rotate by receiving, by using a timing pulley, the power outputfrom the third arm driving unit 302 by a timing belt 307. The second arm112 has a third arm sensor unit 303 for measuring the rotation of thethird arm 113 with respect to the second arm. The third arm sensor unit303 includes an encoder for detecting the rotational position around therotating shaft of the joint connecting the third arm 113 and the secondarm 112, and other sensors. The rotating shaft of this joint has abearing 304.

The first arm 111 supports the second arm 112 by the frame having aC-shaped structure. In this frame, a speed reducer 305 including abearing capable of permitting the moment is arranged on one side, and anauxiliary bearing 306 as an auxiliary member is arranged on the otherside. This makes it possible to disperse the moment generated from theweights of the third arm 113, the second arm 112, the surgicalinstrument manipulator 124, and the robot medical instrument 127, andfrom the external force. A second arm driving unit 309 contained in thefirst frame 111 transmits the power for rotating the second arm 112 by adriving belt 310, thereby rotating the second arm 112 around therotating shaft of the joint (the connecting portion between the thirdarm 113 and the second arm 112). Also, a large hollow structure issecured by distributing the mechanisms in the first frame 111. Thismakes it possible to attach wires and an encoder 308 for detecting therotational position of the second arm 112 with respect to the first arm111. In this example shown in FIG. 3 , the speed reducer 305incorporating the bearing capable of permitting the moment is arrangedin the lower portion of the first frame 111, and the hollow structure isformed in the upper portion. However, these positions may also beswitched.

This embodiment is explained by taking, as an example, the case in whichthe output mechanisms such as the speed reducer 305 and the second armdriving unit 309 are formed into flat shapes in order downsize thehorizontal robot arm 110. For example, it is possible to use a harmonicdrive gear speed reducer or a cycloidal speed reducer capable of highspeed reduction even with a flat shape, a flat motor for which theoutput of the motor itself is raised, or a direct driver motor that canbe attached directly to the joint. As a bearing to be used in the fourrotating joints, a cross roller bearing or a 4-point bearing can be usedso as to downsize the mechanism while permitting the moment.

<Vertical Driving Joint>

FIG. 5 shows a linear-motion joint of the horizontal robot arm 110. Thislinear-motion joint is incorporated into the third frame 103. In alinear-motion mechanism for driving the first arm 111, two ball linearguides 501 are arranged in parallel in the vertical direction. The balllinear guides 501 can sufficiently permit the weight moments of thefirst, second, and third arms 111, 112, and 113 and the external forceswhich the arms receive, and smoothly move these arms.

The first arm 111 is fixed to a support block 502 attached to the balllinear guides 501. A timing belt 505 is fixed to a power transmittingplate 503 extending from the support block 502 supporting the first arm111, and arranged parallel to the ball linear guides 501. A drivingmotor 504 transmits a rotating power to the timing belt 505 and drivesthe timing belt 505 by a timing pulley, thereby actively moving thesupport block 502 supporting the first arm forward and backward in thevertical direction. A position detection control unit 510 including anencoder measures the vertical moving amount of the first arm 111 basedon the moving amount of the driving belt 505 having moved forward andbackward. Also, the position detection control unit 510 includes abraking mechanism, and brakes the motion of the support block 502 (thatis, the linear motion of the horizontal robot arm 110) so as to maintainthe posture. Note that an example using the braking mechanism will beexplained in this embodiment, but the braking mechanism need not alwaysbe used. In this case, a state in which the driving motor 504 isgenerating a driving force for maintaining the posture is maintained. Acounterweight 507 is connected to the power transmitting plate 503 by aretraction wire 506 supported by a support pulley 511.

The counterweight 507 can suppress the output of the driving motor 504for driving the first, second, and third arms 111, 112, and 113, thesurgical instrument manipulator 124, and the robot medical instrument127, by compensating for the weights of these members. The counterweight507 according to this embodiment will be explained in more detail below.In addition to a manipulation from a handheld medical instrumentmanipulated by an operator, the horizontal robot arm 110 must manuallybe moved directly when preparing a surgery or in case of emergency. In acase like this, a horizontal driving joint can easily be moved by humanhands by only releasing the brake. When the brake of a vertical drivingjoint is released, however, a large weight of the horizontal robot arm110 must be held by human hands. Therefore, the vertical driving jointshown in FIG. 5 includes the counterweight 507 for compensating for theweight of each member. This makes it possible to reduce the output tothe driving member, and manually move the robot arm without feeling theweight of the robot arm. Note that the use of the counterweight 507 isnot essential, and a constant load spring may also be used.

Note that when manually moving the robot arm, it is possible to use anassisting system that outputs only power equivalent to the weight of therobot arm in the vertical-axis direction by using a program. When thesystem is down, however, it may be difficult to manually move the robotarm. By contrast, the counterweight 507 is separated from the system bya logic circuit for releasing the brake and shutting off power supply tothe motor. Accordingly, the robot arm is manually movable even when asystem error occurs.

Between the two ball linear guides 501 arranged parallel to each other,the third frame 113 includes a cable guide 509 that assists a linearmotion of wires in order to connect a signal line and a power line tothe third arm 113.

Note that the linear motion mechanism shown in FIG. 5 uses ahigh-efficiency timing belt pulley in order to facilitate manipulations(back drive ability) from the output side. However, it is also possibleto use a ball screw having a large lead, or a high-efficiency slidescrew.

<Grip with Brake Release Switch>

In addition to the weight compensation mechanism (the counterweight 507)for making a manual movement of the robot arm possible in accordancewith the situation, the horizontal robot arm 110 according to thisembodiment includes a brake release switch 311 for facilitating a manualmanipulation of the robot arm. As shown in FIG. 6 , the brake releaseswitch 311 forms a grip with a switch capable of vertically andhorizontally moving the robot arm when grasped with one hand. As will bedescribed later, the brake release switch 311 can be pressed in multipledirections so that a manipulator can press the switch with an almostconstant posture, even when the robot arm variously changes its posturewith respect to the manipulator.

The brake release switch 311 is arranged in the distal end portion ofthe third arm 113. The brake release switch 311 includes a switch forreleasing a holding brake attached to each joint of the horizontal robotarm 110, and a cylindrical grip to be grasped by an operator or thelike.

For safety's sake, the brake for maintaining the posture of the robotarm is released only while the brake release switch 311 is pressed. Notethat instead of the brake, it is also possible to temporarily decreasethe driving force for maintaining the posture. To implement a brake likethis, the brake release switch 311 according to this embodiment has astructure by which an operator can stably keep pressing the switch whileadding a force for moving the distal end portion of the horizontal robotarm 110. The brake release switch 311 shown in FIG. 6A has a shape that,when an operator grasps the switch with a hand as shown in FIG. 6B,facilitates a horizontal movement of the horizontal robot arm 110,sliding of a horizontal rotation caused by the horizontal movement, andaddition of a force in the vertical direction to the horizontal robotarm 110. As shown in FIG. 7 , switches are arranged on the circumferenceof a cylindrical portion of the brake release switch 311, in order tostably press the switch while permitting sliding of a horizontalrotation.

The grip of the brake release switch 311 according to this embodiment isformed into a cylindrical shape, and it is assumed that an operatorholds the grip so as to sandwich it between the thumb and the middlefinger or the thumb and the index finger. In this case, in order topermit sliding of the rotation of the grip when the horizontal robot arm110 is horizontally moved, the grip has a mechanism that can react inany direction with contact by which the grip is sandwiched between thetwo fingers in almost parallel. A manipulator can also grasp the grip soas to cover the whole brake release switch 311 (so that the five fingerscome in contact with the cylindrical portion).

FIGS. 7A to 7C show the internal structures when the brake releaseswitch 311 is viewed in the vertical direction. In an example shown inFIG. 7A, general tact switches 701 are circularly equally arranged, andthe outer circumference is surrounded by levers 702 each having arotation fulcrum 703. In a position farthest from the fulcrum, thepushing amount of the lever 702 is largest, and the force is easilyadded in the direction of pressing the tact switch 701. However, theforce of pressing the tact switch 701 decreases as the position comescloser to the rotation fulcrum. Therefore, an odd number of three ormore pairs of the tact switches 701 and the levers 702 are arranged atequal intervals. This makes it possible to press the tact switch 701 byone of the two fingers regardless of the direction in which the grip isheld.

Note that the lever 702 need not have the rotation fulcrum and may alsobe pushed parallel toward the center of the grip. As described above,however, an odd number of three or more levers are desirably arranged.

FIG. 7B shows an example in which an odd number of three or more tactswitches 701 are arranged at equal intervals, and the outercircumference is surrounded by an elastic resin 705, so that the tactswitch 701 is pressed regardless of the direction in which the grip isheld. In this example, the number of the tact switches 701 is largerthan that of the example shown in FIG. 7A, in order to obtain a highswitch sensitivity. In an example shown in FIG. 7C, a general belt-likepressure-sensitive switch 704 (that changes the resistance value whenpressurized) is arranged in a cylinder, and the outer circumference issurrounded by the elastic resin 705. Accordingly, the switch can bepressed regardless of the direction in which the grip is held.

<Vector Manipulation Mode>

The brake release switch 311 shown in FIGS. 6 and 7 facilitatesmanipulating the robot arm when largely moving the horizontal robot arm110 or after the robot medical instrument 127 is inserted into therobot-side sheath tube 125. On the other hand, in a state in which thedistal end portion of the robot medical instrument 127 is not insertedinto the robot-side sheath tube 125, the directions of the surgicalinstrument manipulator 124 and the robot medical instrument 127 areunstable because the 2-axis gimbal mechanism 301 is a passive joint.This sometimes makes manipulation difficult when inserting the robotmedical instrument 127 into the robot-side sheath tube 125.

In this embodiment, therefore, two input switches are formed on thesurgical instrument manipulator 124 as the distal end of the 2-axisgimbal mechanism 301 as shown in FIG. 8 , and there is provided a vectormanipulation mode in which the whole robot arm can be manipulated basedon manipulations on these input switches.

The two input switches represent only the forward and backwarddirections, and an operator can input an instruction by pressing one ofthese forward and backward switches while supporting (touching) thedistal end of the 2-axis gimbal mechanism 301 with a hand. Thehorizontal robot arm 110 moves the distal end of the robot arm in adirection matching the pressed direction on the axis of the shaft of therobot medical instrument 127. Since, therefore, the surgical instrumentmanipulator 124 functions as a manipulating unit for manuallymanipulating the 2-axis gimbal mechanism 301, the progressing directionof the whole robot arm can be determined. In other words, the horizontalrobot arm 110 controls the motion in accordance with the axial directionof the shaft of the robot medical instrument 127, and with the directionindicated by an instruction on the switch with respect to the axialdirection of the shaft. This makes it possible to easily and smoothlyinsert the distal end portion of the robot medical instrument 127 intothe robot-side sheath tube 125. Also, when removing the distal end ofthe robot medical instrument 127 from the body cavity, a removing actionthat minimizes the contact to an organ can be performed by using thisvector manipulation mode.

Note that an example in which the brake release switch 311 and thevector manipulation mode are used in the horizontal robot arm 110 hasbeen explained above, but the same can apply even when using theendoscope holder 114 and the linear-motion robot arm 120.

The mechanism described above with reference to FIGS. 3 to 5 becomes a5-axis mechanism equivalent model shown in FIG. 9 by connecting thesurgical instrument manipulator 124 and the robot medical instrument 127to the mechanism. The degrees of freedom of two axes are fixed byinserting the distal end portion of the robot medical instrument 127having the degrees of freedom of five axes into a sheath tube attachedto the abdominal region of a patient. Accordingly, it is possible tothree-dimensionally control the position of the distal end portion ofthe robot medical instrument 127 in the body cavity of the patient,while using an insertion point 901 as the reference point of theinsertion depth and the insertion angle.

(Details of Linear-Motion Robot Arm)

<Linear Driving Joint>

Details of the linear-motion robot arm 120 will be explained withreference to FIGS. 10 to 12 . As shown in FIG. 10 , the third arm 123and the second arm 122 are connected by two ball linear guides 1001arranged parallel in the horizontal direction, in order to sufficientlypermit the weight moment and the external force which the linear-motionrobot arm 120 receives, and implement a smooth motion.

A driving unit 1002 fixed to the second arm 122 and including a speedreducer and a motor drives the third arm 123. The other end is fixed tothe end of the third arm 123, so the driving unit 1002 can linearly movein the horizontal direction. A third arm sensor unit 1008 measures theforward/backward motion of the third arm 123 based on a change in thirdarm driving belt 1009 driven by the driving unit 1002. This timing beltpulley and a cable guide for assisting the linear motion of wires areincorporated into the second arm 122 and the third arm 123. A cableguide 1010 that assists the linear motion of wires in order to connect asignal line and a power line to the third arm 123 is installed betweenthe two ball linear guides 1001 arranged parallel to each other.

Like the horizontal robot arm 110, a 2-axis gimbal mechanism 1003 havingan encoder is attached to the distal end of the third arm 123, and theendoscope holder 114 can be attached on the axis of the 2-axis gimbalmechanism 1003. A generally used endoscope 1004 can be attached to theendoscope holder 114. Endoscopes manufactured by various manufacturersand having various functions and shapes can be attached to the surgerysupporting apparatus by using the endoscope holder 114 matching theendoscope shape as needed. Also, a brake release switch 1011 is arrangednear the distal end of the third arm 123.

A first arm connecting plate 1006 attached via a connection bearing 1005capable of permitting the moment includes a speed reducer 1007. Ahorizontal rotation can be performed around the rotating axis in thevertical direction by transmitting the power of a second arm drivingmotor 1012 by a timing belt pulley. Note that it is also possible todirectly attach a speed reducer having a hollow structure capable ofpermitting the moment to the connecting portion between the first arm121 and the second arm 122 without using the first connecting plate1006.

The 2-axis gimbal mechanism 1003 at the distal end portion of the thirdarm 123 is a passive joint having no power unit, like the horizontalrobot arm 110. However, it is possible, by using absolute encoders forboth of the two axes, to obtain the position of the robot medicalinstrument 127 by using the forward kinematics. It is also possible touse an elastic mechanism (a damper, a resin spring, or a metal spring inthe rotating direction) or an auxiliary power in order to suppress theinfluence of slight vibrations during robot arm manipulation or slightmotions caused by the respiration of a patient, thereby achieving afunction of stabilizing the posture or avoiding a unique posture.

<Vertical Driving Joint>

The vertical driving joint of the linear-motion robot arm 120 will beexplained below with reference to FIG. 11 . The first arm 121 is drivenby a nut rotation type ball screw. Therefore, a ball screw shaft 1101 isfixed to the second frame 102, and the lower portion of the first arm121 as the driving side has a driving unit 1102 including a nut formaking rotation possible, a motor for driving the nut, a speed reducer,and an encoder. A generally used mechanical part can be used as this nutrotation type ball screw.

Like the horizontal robot arm 110, the first arm 121 includes acounterweight 1103 that is connected by a wire and compensates for theweight. This makes it possible to suppress the output of the motor inthe driving unit 1102, and easily move the robot arm by a direct-contactmanual manipulation. Two or more counterweights 1103 are divisionallyarranged in the second frame 102 via a support pulley 1106 or the like.This effectively downsizes the whole apparatus while increasing thesafety of the wire. A cable guide 1105 assists the motion of a cable orthe like extending from the second frame 102 to the first arm 121. Notethat the use of the counterweight 1103 is not essential, and a constantload spring may also be used.

The first arm 121 is connected to the second arm 122 via a connectingportion 1104. The second arm 122 is so connected as to be rotatablearound the vertical axis of the connecting portion 1104.

A 5-axis mechanism equivalent model as shown in FIG. 12 is obtained byconnecting, via the endoscope holder 114, an endoscope 1004 to themechanism of the linear-motion robot arm 120 shown in FIGS. 10 and 11 .The distal end portion of this endoscope having the degrees of freedomof five axes is inserted into the robot-side sheath tube 125 attached tothe abdominal region of a patient. Consequently, it is possible to fixthe degrees of freedom of two axes, and three-dimensionally control theposition of the distal end portion of the endoscope in the body cavitywhile using the insertion point as the rotation center.

(Sharing of Screw Shaft)

A laparoscopic surgery is applied to various diseases, and its surgicalmethods are also various. The operating table 151 shown in FIG. 1B canbe moved in the vertical direction by about a maximum of 500 mm inaccordance with the surgical method, the body shape of a patient, theheight of an operator, and the like. The surgery supporting apparatusaccording to this embodiment can secure a motion amount corresponding tothe height of the operating table that changes in accordance with achange in situation.

Generally, the height of the whole apparatus increases in order tosecure a wide motion amount. However, the height of the operating tabledoes not always change during a surgery, but is determined at the startof a surgery by factors such as the surgical method mentioned above, anddoes not often change during the surgery. In this embodiment to beexplained below, therefore, a motion range that is always movable duringa surgery and a motion range that is changed in accordance with theheight of the operating table are mechanically separated and at the sametime shared as well. This makes it possible to secure a sufficientmotion range while reducing the apparatus size. More specifically, FIG.13 schematically shows the relationship between the first arm 121 of thelinear-motion robot arm 120 and the two frames (the second frame 102 andthe third frame 103) according to this embodiment. FIG. 14A shows theway the horizontal robot arm 110 is attached to the third frame.

For example, to cause the vertical driving joint of the horizontal robotarm 110 to have a motion range including both the change in height ofthe operating table 151 and the motion range of the surgical instrumentmanipulator, a high frame is necessary, and the height of thelinear-motion robot arm 120 increases accordingly. When the height ofthe operating table has changed, therefore, the height is adjusted byvertically moving the third frame 103. When controlling the motion ofthe handheld medical instrument 131, two steps of strokes can be ensuredby individually vertically moving the two horizontal robot arms 110(that is, the first arms 111) connected to the third frame 103. As shownin FIGS. 13 and 14A, not only the height but also the whole apparatussize can be decreased by attaching the third frame 103 and the first arm121 of the linear-motion robot arm 120 to a common support member sothat these members can move forward and backward.

FIG. 14B is a sectional view showing the frames according to thisembodiment. The third frame 103 and the first arm 121 of thelinear-motion robot arm 120 have U-shapes so that they can be overlappedwhile maintaining a high rigidity with respect to the moment in afalling direction. Furthermore, the apparatus can be downsized bysharing parts by arranging the ball screw shaft 1101 in the center ofthe apparatus.

Generally, many ball screws are linearly moved by attaching a bearing tothe end of the shaft, fixing a nut to the driving side, and rotating thescrew shaft. On the other hand, this embodiment uses a nut rotation typeball screw to make two linear motions (that is, the linear motions ofthe third frame and the first arm 121) possible by using one screw shaft1101. Since the screw shaft is shared, when the third frame 103 rises,the first arm 121 of the linear-motion robot arm 120 rises accordingly,so the lower-limiting motion range of the first arm 121 narrows.However, practically no problem arises because the first arm of thelinear-motion robot arm 120 does not require the lower-limiting motionrange any longer in accordance with the height of the operating table151. That is, since one screw shaft 1101 is shared in the linear motionsof the third frame and the first arm 121, it is possible to downsize theapparatus and decrease the cost without any practical inconvenience suchas a restriction on the robot arm movable range required for a surgery.

(Motion Range of Each Robot Arm)

Partial spherical ranges 1501 to 1503 shown in FIGS. 15A and 15Brepresent examples of the movable range of the arm distal end portion ofeach robot arm when inserting the robot medical instrument 127 into abody cavity. The center of this spherical range is a position where asheath tube is inserted into the abdominal region of a patient. A locuscorresponding to the surface of the spherical range expresses the armdistal end portion in a position where the distal end portion of therobot medical instrument 127 is extracted most from the robot-sidesheath tube 125. Although the movable range of a robot arm alone differsfrom this, if the arm distal end is moved away from the sheath tubeinsertion position by a distance longer than the length of the shaft ofthe robot medical instrument 127, the surgical instrument distal endportion is pulled out from the sheath tube. Accordingly, each sphericalrange shown in FIGS. 15A and 15B indicate a maximum movable range of thearm distal end portion when inserting the robot medical instrument 127.

A space 1505 immediately above an insertion point 1504 of the robotmedical instrument 127 with respect to the sheath tube is a uniqueposture of the 2-axis gimbal mechanism 301 and hence is excluded fromthe movable range. The linear-motion robot arm 120 supporting theendoscope 1004 has a similar movable range (for example, 1503), but hasa symmetrical spherical motion range in order to minimize interferencewith the movable range of the horizontal robot arm 110. In an actualsurgical method, the robot arm does not always move in this motion rangebut intensively moves in the lower abdomen or the upper abdomen.Therefore, the range of a shape about half the spherical range ispresumably a constant motion range. As shown in FIG. 15A, the movableranges of the arm distal end portions largely overlap each other, so thehorizontal robot arm 110 having a symmetrical structure with respect tothe vertical plane is suitable. The vertical robot arm 120 is suitablefor an arm capable of supporting the endoscope 1004 so as to avoid thesemovable ranges.

As is apparent from FIG. 1B described earlier, the arrangement thatsuppresses the interference of each robot arm from the movable range ofthe distal end portion of the robot arm when inserting a surgicalinstrument can avoid interference to the skill of an operator whoperforms a treatment by using the handheld medical instrument 131 ormanipulates the robot arm supporting the robot medical instrument 127,and at the same time can secure a sufficient motion range. Note that thelinear-motion robot arm 120 supporting the endoscope 1004 has a similarmovable range (1503), and the movable range sometimes contains the handof an operator. Since, however, the endoscope moves so as to shift thedistal end of the handheld medical instrument 131, the direction of theendoscope matches the direction of the handheld medical instrument 131.That is, the interference between the direction of the endoscope and thehandheld medical instrument 131 can be suppressed.

Note that each movable range shown in FIG. 15 is an example, so themovable range need not strictly be this range and can be reduced,enlarged, or deformed within the mechanical motion limiting range of therobot arm in accordance with a surgical method or the like.

(Fault Detection System for Robot Arm Having Active Joint)

The surgery supporting apparatus 200 described above can further includea fault detection system for the active joint of each robot arm. Toimplement this fault detection system, a servo motor having anincremental encoder is used as all motors for driving each robot arm.Also, a spring-actuated brake is installed on the input side or theoutput side of a speed reducer, and an absolute encoder is installed onthe output side.

When a motion instruction is given to the robot arm in an arrangementlike this, it is only necessary to determine whether a difference isdetected between the command value of the motor and the motion amount onthe output side. If it is determined that the difference is detected, itis possible to detect a power transmission abnormality between the motorand the speed reducer, a damage of the speed reducer, and a powertransmission abnormality from the speed reducer to the final outputshaft. Note that power transmission herein mentioned includes, forexample, a gear, a timing belt pulley, a ball screw, and a wire.

On the other hand, even in a standby state in which no motioninstruction is given to the robot arm, a difference can be detectedbetween the output-side encoder and the motor encoder when applying theexternal force to the robot arm. When the external force is given,therefore, whether a difference is detected between the output-sideencoder and the motor encoder is determined. If it is determined thatthe difference is detected, an abnormality such as the external contactof the robot arm is detected.

(Initialization Process)

Each robot arm of this embodiment has a passive joint. As describedabove with reference to FIGS. 9 and 12 , therefore, when a surgicalinstrument is inserted into a sheath tube attached to the abdominalregion of a patient and the insertion point 901 is determined, thecontrol unit 201, for example, can calculate and specify the position ofthe distal end of the robot medical instrument 127 in the body cavity.For example, as shown in FIG. 16 , an initialization process isperformed on each robot arm following a predetermined procedure. Thismakes it possible to allocate an inserted sheath tube, and obtainposition information of the insertion point 901 necessary to control therobot arm.

A series of operations of the initialization process will be explainedwith reference to FIG. 17 . Note that the control unit 201 executes theoperations of an initialization mode shown in FIG. 17 by mapping aprogram stored in the storage medium 204 to the memory 205 and executingthe program. This initialization process is started in a state in which,for example, the operation mode of the surgery supporting apparatus isset to the initialization mode beforehand by a manipulation performed onthe manipulation unit 202 (for example, a foot switch) by an operator.

In step S1701, the control unit 201 detects an instruction (for example,switch pressing) by contact of the operator on the brake release switch311 of the first robot arm not inserted into the robot-side sheath tube125, or on the vector manipulation switch 801.

In step S1702, the control unit 201 performs robot arm controlcorresponding to the initialization mode. In accordance with the pressedswitch, the control unit 201 can also switch to one of the brake releasemode and the vector manipulation mode included in the initializationmode. For example, when the brake release switch 311 is pressed, thecontrol unit 201 sets the operation mode to the brake release mode, andcontrols the target robot arm so as to release the brake of the robotarm. When the vector manipulation switch 801 is pressed, the controlunit 201 switches the operation mode to the vector manipulation mode,and controls the robot arm in accordance with the instruction on thevector manipulation switch 801.

In step S1703, the control unit 201 determines, in an initializationmode for a specific robot arm, whether the brake release switch 311 orthe vector manipulation switch 801 of another robot arm is pressed. Thecontrol unit 201 advances to step S1704 if it is determined that thebrake release switch 311 or the vector manipulation switch 801 ofanother robot arm is pressed, and advances to step S1705 if not.

In step S1704, in the initialization mode, the control unit 201 causesthe display unit 203 to display a warning message indicating aninstruction to move robot arms one at a time. This warning is notlimited to the display on the display unit 203, and it is also possibleto generate a warning sound from a voice output unit (not shown), orgive tactile feedback to another manipulated robot arm.

In step S1705, the control unit 201 monitors insertion of the robotmedical instrument 127 into the robot-side sheath tube 125, based on theoutput from the robot-side insertion depth measurement unit 126.

In step S1706, the control unit 201 controls the motion of the robot armin accordance with a manual manipulation (a manipulation on the gripincluding the brake release switch 311 or a manipulation on the vectormanipulation switch 801) performed by an operator, thereby inserting therobot medical instrument 127 into the robot-side sheath tube 125.

In step S1707, the control unit 201 detects from the robot-sideinsertion depth measurement unit 126 that the robot medical instrument127 is inserted into the robot-side sheath tube 125 into which nothingis inserted. In step S1708, the control unit 201 associates the manuallymanipulated robot arm with the robot-side sheath tube 125 whoseinsertion has been detected.

In step S1709, based on a signal from the associated robot-side sheathtube 125, the control unit 201 determines whether the robot arm isextracted from the robot-side sheath tube 125. The process advances tostep S1710 if it is determined that the robot arm is extracted, andadvances to step S1711 if not. In step S1710, the control unit 201causes the display unit 203 to display a warning message indicating aninstruction not to extract the robot arm until the initializationprocess is complete.

In step S1711, the control unit 201 calculates the position of theinsertion point 901. This calculation of the position of the insertionpoint will be described later. In step S1712, the control unit 201determines whether the robot arms are associated with all the robot-sidesheath tubes 125. If it is determined that the robot arms are notassociated with all the robot-side sheath tubes 125, the process returnsto step S1701. On the other hand, if it is determined that the robotarms are associated with all the robot-side sheath tubes 125, thecontrol unit 201 switches the operation mode of the surgery supportingapparatus to the original operation mode, and terminates theinitialization process.

Two methods will be explained below as examples of the method ofcalculating the insertion point 901 in step S1711 of the initializationprocess. In one method, the position of the robot medical instrument 127detected by a robot-side insertion depth measurement unit that alsooperates as an insertion detection sensor is regarded as an insertionpoint. In this method, the control unit 201 can calculate the positionof the insertion point in a robot coordinate system by using the forwardkinematics from each link length, each surgical instrument length, andeach joint angle.

The other method is to perform the calculation from the posture of asurgical instrument manipulator. As shown in FIG. 18 , assume that therotation centers of a gimbal mechanism in two given postures are P₁ andQ₁, and the corresponding distal end coordinates of the robot medicalinstrument 127 are P₂ and Q₂. Ideally, the rotation centers in thesepostures are supposed to match. As shown in FIG. 18 , however, therotation centers become twisted positions due to, for example,deflection of the abdominal wall. Therefore, this method uses a point xbetween these postures as the insertion point (rotation center).

To obtain the coordinates of the insertion point x, points S₁ and S₂ atwhich perpendicular lines extending from straight lines intersect eachother are calculated in accordance with the following equations:

$\begin{matrix}\begin{matrix}{d_{1} = \frac{{n_{1} \cdot {PQ}_{11}} - {( {n_{1} \cdot n_{2}} )( {n_{2} \cdot {PQ}_{11}} )}}{1 - ( {n_{1} \cdot n_{2}} )^{2}}} \\{d_{2} = \frac{{( {n_{1} \cdot n_{2}} )( {n_{1} \cdot {PQ}_{11}} )} - {n_{2} \cdot {PQ}_{11}}}{1 - ( {n_{1} \cdot n_{2}} )^{2}}} \\{S_{1} = {P_{1} + {d_{1}n_{1}}}} \\{S_{2} = {Q_{1} + {d_{2}n_{2}}}}\end{matrix} & (1)\end{matrix}$

where n₁ and n₂ represent unit vectors representing the postures of thesurgical instrument manipulator, and PQ₁₁ represents a vector extendingfrom P₁ to Q₁.

When the points S₁ and S₂ are obtained, the point x between them can beobtained by:

$\begin{matrix}{x = \frac{S_{1} + S_{2}}{2}} & (2)\end{matrix}$

Even when obtaining the position of the rotation center from a largernumber of postures, it is possible to obtain intermediate points by amethod similar to the above method, and use the average value as therotation center.

In step S1711, the control unit 201 calculates the position of theinsertion point by using one or both of the abovementioned calculationmethods. Consequently, the control unit 201 can specify the position ofthe robot-side sheath tube 125 on the spatial coordinate system (robotcoordinate system) of the surgery supporting apparatus 200, and cancontrol the motion of each robot arm in accordance with the angle anddepth of insertion of the handheld medical instrument into the bodycavity.

Note that the insertion point may fluctuate on the robot coordinatesystem during a surgery due to, for example, a slight motion of theperitoneum of a patient. In this embodiment, however, the robot arm hasthe 2-axis gimbal mechanism 301 of a passive joint. This makes itpossible to follow and detect a slight movement of the insertion point(unlike a robot arm that supports the insertion point by an RCM (RemoteCenter of Motion) mechanism). When the position of the insertion pointfluctuates, the control unit 201 executes the calculation method shownin FIG. 18 at a predetermined time interval in a loop that controls therobot arm by using a handheld surgical instrument. Consequently, adeviation of the insertion point 901 on the robot coordinate system canbe corrected. That is, the manipulation accuracy of the distal endportion of the robot medical instrument 127 can be held high.

Note that the position of the operator-side sheath tube 135 can beobtained by a method different from the method of specifying theposition of the insertion point of the robot-side sheath tube 125, andcan also be obtained by using a robot arm to be inserted into therobot-side sheath tube 125. For example, after each robot arm and thecorresponding robot-side sheath tube 125 are initialized, one of the tworobot medical instruments 127 is extracted from the allocated sheathtube and inserted into the operator-side sheath tube 135. As aconsequence, position information of the operator-side sheath tube 135on the robot coordinate system can be obtained.

(Semiautomatic Retraction Mode)

As described above, the surgery supporting apparatus 200 is used toassist the operative procedure of an operator by using a robot arm. Forexample, the use of the surgery supporting apparatus 200 makes itpossible to secure an operation field by holding an organ and fixing itin the place by the robot medical instrument 127, perform suturing bycausing the robot medical instrument 127 to hold a needle and a thread,or move an endoscope to an intended position.

A semiautomatic retraction mode of the surgery supporting apparatus 200will be explained below by taking, as an example, a state in which anorgan is pulled and fixed by the robot medical instrument 127. Anoperator performs a treatment (generally, dissection or the like) on anorgan. Since, however, the robot medical instrument 127 is spatiallykept fixed, the retraction force sometimes weakens when dissectionprogresses and the shape of the organ changes. A surgery by an operatorcan be performed more smoothly if the retraction force on an organ cansimply be adjusted in accordance with the progress and status of thesurgery, in the same manner as when a human performs retraction as anassistant.

In the semiautomatic retraction mode of the surgery supporting apparatus200, therefore, the retraction force when using the robot medicalinstrument 127 can simply be adjusted. Note that a case in which anoperator uses a switch attached to the handheld medical instrument 131included in the manipulation unit 202 in order to switch the operationmode of the surgery supporting apparatus 200 to the semiautomaticretraction mode will be explained as an example, but anothermanipulating means may also be used. Switching is not limited to aphysical switch and may also be based on voice recognition or gesturerecognition.

First, an operator controls the robot arm by using, for example, asurgical instrument to be used in a treatment, and causes the robotmedical instrument 127 to pull an organ. In this case, the control unit201 temporarily records the locus of the distal end coordinates of therobot medical instrument 127, from the start to the end of themanipulation on the robot medical instrument 127, in the memory 205.Based on the recorded locus, the control unit 201 calculates a direction(called a retraction direction) in which the distal end is movingimmediate before the end of the manipulation. However, the retractiondirection is not limited to the direction obtained by last sampling, butcan also be a direction obtained by integrating or averaging themovement of the distal end position during a predetermined periodimmediately before the end of the manipulation.

When detecting the manipulation of switching to the semiautomaticmanipulation mode, the control unit 201 controls the robot arm such thatthe distal end coordinates of the robot medical instrument 127 move inonly a predetermined direction matching the retraction direction (thatis, restricts the movement of the distal end position of the medicalinstrument 127). More specifically, in a normal operation mode in whichthe distal end position of the robot medical instrument 127 iscontrolled by using a surgical instrument, a manipulation must beperformed by using a 6-degree-of-freedom positioning surgicalinstrument. When using the semiautomatic retraction mode, however, theretraction force can be adjusted by performing only a1-degree-of-freedom manipulation.

The adjustment of the distance and the speed at which the distal endposition is moved in the retraction direction in the semiautomaticretraction mode is not limited to the manipulation using a surgicalinstrument, and it is also possible to use a foot switch or the like ofthe manipulation unit 202 or add a new switch or the like. For example,in the semiautomatic retraction mode, the control unit 201 can performcontrol in a direction of increasing the retraction force if it isdetected that a surgical instrument held by an operator is rotatedclockwise around the shaft, and can perform control in a direction ofdecreasing the retraction force if it is detected that the surgicalinstrument is rotated counterclockwise. Another method may also be usedas long as the method can change a 1-degree-of-freedom velocity.

In the surgery supporting apparatus according to this embodiment as hasbeen explained above, the posture of the robot medical instrument 127that is inserted into a body cavity and mechanically drivable can becontrolled by using the handheld medical instrument 131 to be insertedinto the body cavity. When the operation mode of the surgery supportingapparatus is the robot arm manipulation mode, the motion of the robotarm is controlled in accordance with the posture of the handheldsurgical instrument. On the other hand, when the operation mode is themanual manipulation mode, the motion of the robot arm is controlled inaccordance with a manual manipulation on the robot arm. This makes itpossible to provide a surgery supporting apparatus not requiring aconsole that is difficult to install in an operating room, and capableof simply manipulating a robot arm. In addition, manipulations can beperformed by a minimum number of operators, so the interference betweenthe robot arm and the operators can be reduced.

Furthermore, the frame to which the horizontal robot arm is attached andthe forward/backward motion in the vertical direction of thelinear-motion robot arm are implemented by the common support member.This can downsize the surgery supporting apparatus and reduce the cost.

Note that the parts of the above-described surgery supporting apparatuscan also be implemented as they are separated or integrated. Note alsothat the disclosed embodiments can include a case in which a controlunit including one or more processors reads out a program of a computerthat executes the above-described processing from a storage medium andexecutes the readout program, and a case in which the program isobtained by wired communication or wireless communication and executed.

It is to be understood that the invention is not limited to thedisclosed exemplary embodiments. The scope of the following claims is tobe accorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

What is claimed is:
 1. A surgery supporting apparatus comprising: arobot arm comprising a gimbal mechanism configured to rotate around tworotational axes at a distal end portion of the robot arm, the robot armbeing configured to three-dimensionally move a surgical instrumentattached to the robot arm via the gimbal mechanism; and one or moreprocessors programmed to: control a motion of the robot arm so as tocontrol a posture of the surgical instrument, control an insertion angleand an insertion depth of the surgical instrument into a body cavity;and calculate a reference point of the insertion depth and the insertionangle based on rotation centers of the gimbal mechanism in two or morepostures.
 2. The surgery supporting apparatus according to claim 1,further comprising: a vector manipulation switch configured to receivean instruction by contact of an operator, wherein the one or moreprocessors are further programmed to control the motion of the robot armwith respect to an axial direction of a shaft of the surgical instrumentin accordance with the instruction.
 3. The surgery supporting apparatusaccording to claim 1, wherein the one or more processors are programmedto calculate the reference point when the surgical instrument isinserted into the body cavity.
 4. The surgery supporting apparatusaccording to claim 3, wherein the one or more processors are programmedto calculate the reference point when an insertion detection sensordetects that the surgical instrument is inserted into a sheath tubeattached to an abdominal region of a patient.
 5. The surgery supportingapparatus according to claim 1, wherein the robot arm comprises: a firstrobot arm comprising: a first arm having a degree of freedom in avertical direction; a second arm connected to the first arm by a jointhaving a degree of freedom in horizontal rotation; and a third armconnected to the second arm by a joint having a degree of freedom inhorizontal rotation; and a second robot arm comprising: a fourth armhaving a degree of freedom in the vertical direction; a fifth armconnected to the fourth arm by a joint having a degree of freedom inhorizontal rotation; and a sixth arm connected to the fifth arm by ajoint having a degree of freedom in horizontal direction.
 6. The surgerysupporting apparatus according to claim 5, further comprising: a firstframe to which the first arm is attached; and a second frame to whichthe fourth arm is attached, wherein the first frame is attached to thesecond frame so that the first frame is movable vertically with respectto the second frame.
 7. The surgery supporting apparatus according toclaim 6, wherein: the second frame comprises a shaft extending in avertical direction, and the first frame and the fourth arm areconfigured to move along the shaft.
 8. A surgery supporting apparatuscomprising: a robot arm comprising a gimbal mechanism configured torotate around two rotational axes at a distal end portion of the robotarm, the robot arm being configured to three-dimensionally move asurgical instrument attached to the robot arm via the gimbal mechanism;and one or more processors programmed to: control manipulation of therobot arm so as to control a posture of the surgical instrument, controlan insertion angle and an insertion depth of the surgical instrumentinto a body cavity; and calculate a position of a reference point of theinsertion angle and the insertion depth of the surgical instrument intothe body cavity by using: (i) an insertion position of a distal endportion of the surgical instrument when the surgical instrument isinserted into the body cavity, and (ii) an angle around the tworotational axes of the gimbal mechanism when the surgical instrument isinserted into the body cavity.
 9. The surgery supporting apparatusaccording to claim 8, wherein the one or more processors are programmedto calculate the position of the reference point when an insertiondetection sensor detects that the surgical instrument is inserted into asheath tube attached to an abdominal region of a patient.